Field of the Invention
The present invention relates to variable rate material management for agricultural landscapes. More particularly, but not exclusively, the present invention relates to auto-calibration of real-time sensors used in the application of agricultural products such as agrochemicals and seeds, including soil content sensors.
Problems in the Art
Various methodologies are available to crop producers which allow them to apply agrochemicals. Some methodologies use real-time active crop or soil sensors for variable rate control of agrochemicals and seed rate. Yet problems remain in providing effective calibration of these sensors.
Another problem relates to fact that organic matter content of a soil is a significant variable in modern soil management and relates to a soil's adsorption of pesticides, its water holding capacity, and its yield potential are often related to its organic matter content. By sensing a landscape's organic matter content in real-time, the potential of applying agricultural products without the use of preprocessed maps will allow producers to optimize their use as well as maximizing profitability.
Conventional agricultural equipment is designed to apply chemicals and plant crops at uniform rates within a field, regardless of changes in soil type or organic matter content. This can result in an over application of chemicals in some areas of the field, an under application in other areas, overplanting in some areas and under planting in others. It would therefore be desirable to provide a prescription application system which would rapidly and accurately adjust chemical and seeding rates by sensing variations in soil type and organic matter as equipment traverses a field. There is thus a need for an apparatus that will sense the organic content of soil as chemicals are being applied or crops planted so that the application of the chemicals or the seeding can be adjusted based upon the sensed organic matter content of the particular area of the field to be treated or planted. In the past couple decades, there has been interest in developing agricultural equipment capable of sensing soil organic matter content and adjusting the corresponding application rate of herbicides, seeds or fertilizer as the equipment moves across the field. Such sensing systems require knowledge of the mathematical relationship between organic matter content and soil color. In general, progress in developing such sensor systems has proven to be unsatisfactory because the developers have attempted to develop universal relationships between organic matter content and sensor output. The problem with this approach is that it is known that different soil associations can have different relationships between organic matter content and soil color. Another problem faced in developing an accurate real-time soil organic matter sensor is that the scene, i.e., particular area of the soil that is being observed by the sensor, must have a generally uniform surface. These sensors typically work by reflecting light off the scene. If the surface of the scene is not uniform, the reflectance will vary in response to surface roughness changes yielding erroneous results. Variations in the surface of the scene can be caused by differences in soil texture, size of the soil aggregates, moisture content, etc. Ambient light can also adversely affect the accuracy of such sensors by introducing a second, variable source of light which is also reflected from the scene and picked up by the sensor.
What is needed are systems and methods which are simple and convenient for agricultural producers to use while still resulting in application of agrochemicals and agricultural materials in acceptable and desirable manners.